diff --git a/tads3/vmbiftad.cpp b/tads3/vmbiftad.cpp
index c2f61be..d17b4cb 100644
--- a/tads3/vmbiftad.cpp
+++ b/tads3/vmbiftad.cpp
@@ -2181,7 +2181,7 @@ void CVmBifTADS::toIntOrNum(VMG_ uint argc, int int_only)
         /* the value for "nil" is 0 */
         retval_int(vmg_ 0);
     }
-    else if (len2 == 4 && memcmp(p2, "true", 3) == 0)
+    else if (len2 == 4 && memcmp(p2, "true", 4) == 0)
     {
         /* the value for "true" is 1 */
         retval_int(vmg_ 1);